Field of the Invention
The present invention relates to a transfer system in which an actuator on a moving magnet linear motor carriage is driven.
Description of the Related Art
A transfer apparatus using a linear motor has heretofore been used as a transfer apparatus for transferring a workpiece between operation steps of a production apparatus. The transfer apparatus is configured to, after predetermined processing is performed on the workpiece in each operation step, transfer the workpiece to the next step in sequence. For a case of changing the orientation of the workpiece in a certain operation step, some transfer apparatus is provided, beside the transfer system, with an apparatus for changing the orientation of the workpiece in the middle of transfer of the workpiece or at the operation step. Since such a transfer apparatus changes the orientation of the workpiece by using a workpiece orientation converter in the middle of or after the transfer of the workpiece and then moves the workpiece to the next transfer or processing, there has been a problem that a large installation space needs to be allocated.
Japanese Patent Application Laid-Open No. 2001-179568 proposes a workpiece transfer apparatus provided with an orientation conversion mechanism for converting the orientation of a workpiece by moving a workpiece stage for supporting the workpiece along a guide member. The workpiece transfer apparatus proposed in Japanese Patent Application Laid-Open No. 2001-179568 is provided between machine tools, and uses the orientation conversion mechanism provided between the workpiece stage and the guide member to change the orientation of the workpiece along with the movement of the workpiece stage.
Japanese Patent Application Laid-Open No. H07-86772 proposes a transfer apparatus for transferring a workpiece held between a plurality of carriers. In the transfer apparatus proposed in Japanese Patent Application Laid-Open No. H07-86772, the workpiece is held between the two carriers, and the speeds of the two carriers are controlled according to the speed of one of the two carriers with the slower movement speed.
However, in the workpiece transfer apparatus proposed in Japanese Patent Application Laid-Open No. 2001-179568, the orientation conversion mechanism for each step needs to be installed beside the workpiece transfer apparatus, leading to the need to allocate a large installation space. In Japanese Patent Application Laid-Open No. H07-86772, the plurality of carriers need to be detected and controlled in real time in synchronization with a control cycle. Thus, in the transfer apparatus using the moving magnet linear motor, a system needs to be configured to manage and control positional information of all the carriers on a transfer path. This leads to a problem that the system would be complicated and large.